In the event that a tsunami smashes into a fixed structure such as a reinforced concrete building (referred to below as a building), there is an influx of water into the building from openings such as windows, doors, air supply and exhaust ducts, and the like, which are positioned lower than the wave height of the tsunami.
In such an event, if the openings are disposed at low elevations such as windows and doors, people who live in the building are able to prevent an influx of water by closing the openings before the tsunami arrives (e.g., Patent Reference 1).
However, if openings such as air supply and exhaust ducts are present in an elevated location, and if an air intake and exhaust system such as a ventilation fan is present in the vicinity of the openings, a mechanism for closing the openings becomes complicated. In addition, it takes time to close the openings manually, and the people involved in the closing operation are exposed to danger. Patent Reference 1: Japanese Patent Publication No. 2001-521089